I need to paint the interior of some metal planter boxes with something that will seal them (they are not 100% watertight) and protect them. There was something like that one one of those "as seen on TV" type commercials I am thinking of.

What would all ya'll recommend? I want something I can just paint on and forget, no two part things.

How about a truck bed liner. It fills holes and makes a continuous leak proof coating.

A 2 component fluid applied is what you are looking for, stay away from anything 1 component, they do not last.

If it were me I would just go get some Bituthene or similar which is a self adhered sheet membrane and be done with it.

Do you want them to be water tight?

If you do Gacoroof would be perfect, but I think 1 gallon is the smallest size you can buy. There may be a similar product that's cheaper. It's also 1 part.
http://www.worldofstains.com/GacoRoof-Coat...oof-1-white.htm

If you have an RV the rest could be used on the roof.

Gacodeck (same stuff in colours) on our decks for 3 years, holding up great and no leaks.

You need drainage!

What are you planting? As noted, you need drainage. Put some gravel in the bottom, maybe a piece of landscape fabric on the gravel and call it good to go.

The product in the commercials where the guy waterproofs the row boat is expensive. Very, for the amount you get for your money and the surface has to be 'just so'.

Zinsser Watertite ,great product comes in white but can be tinted,not easy to apply as its like honey....very thick.

You never know what might stunt or kill the plants. The brush will be trashed too. you can prob buy a 5 gal bucket of gravel from a landscape supply for a couple of bucks or if like me, I scrape it out of my driveway. You'll only need a few inches in the bottom.

Try Dial submarine cooler coating. Stuff is made for evaporative coolers. I coated the inside belly of mine 8 years ago and haven't had an issue. Takes a while to dry and smells bad. Comes in Quart size for around $10.

The belly of what? A boat?

The belly of the evaporative cooler also known as a swamp cooler.

That's the one you need read the instructions for use before you buy it. There is cleaning/degreasing/scuffing the area to be coated with sandpaper/multiple coats and dry times involved.

Back for some help with this project. Making more planters. Bigger now, but no bottoms, as they sit over open ground. 1" angle iron with 16 gauge steel. I MIGGED the sides in using a spiral pattern (as opposed to just welding in straight lines) and am getting bad oil canning.

My question is about shrinking the panels to make them tight. Whats the best way. Heat with a torch? Shrinking disk
?